Common precision casting defects have bubbles, bubbles are fine castings individual position showing lubrication hole eye defects. Bubbles are usually found after machining. Kyrgyzstan state precision casting technical staff separation years of experience in the workshop, the precision casting of the reasons for the emergence of bubbles and preventive measures are summarized as follows: First, the composition of the reasons: 1. Most of the conditions of the bubble is mainly due to fine casting shell shell is not abundant, Pouring molten steel when the shell suddenly produce a large number of gas can not be successfully discharged, and then into the metal liquid to form bubbles; 2. Shell or shell due to shell information reasons, shell permeability is too bad, the cavity of the gas is difficult to discharge into the metal In the formation of bubbles; 3. pouring into the molten steel in the air can not be discharged to form the casting bubbles. Second, the precautionary measures 1. In the case of precision casting conditions permit, in the construction of complex casting at the highest set of exhaust bubbles. 2. In the design of the pouring system, to be fully aware of the shell exhaust demand. 3. Shell firing temperature, time should be reasonable, the insulation time should be sufficient. 4. Wax should be completely removed when the wax material. 5. Properly reduce the pouring mouth to the gate cup spacing, pouring the speed to be uniform, to ensure that the degree of steel steady overflow cavity, as little as possible into the molten steel in the air, so that the cavity and the molten steel can be successfully discharged.